Researchers from Duke University and Imperial College London recently conducted an experiment, published in The Lancet journal, to determine how taking a stroll outside can can affect the respiratory and cardiovascular systems, particularly among older adults.

To do so, they examined 119 individuals over the age of 60, who were either healthy, had stable coronary heart disease or had stable ischemic heart disease. They asked the volunteers to walk for two hours midday in one of two locations in London. One was a quieter area in Hyde Park, while the other was along a busier section of Oxford Street, where pollution usually exceeds the air quality limits set by the World Health Organization.

After analyzing the results, they found those who paraded around Hyde Park saw significant lung capacity improvement within the first hour of exercise, which often lasted for more than 24 hours.

On the other hand, those on Oxford Street experienced a smaller increase, and their results did not last for the rest of the day.

Furthermore, they discovered walking in Hyde Park reduced arterial stiffness by more than 24 percent for both healthy and coronary heart disease patients. It decreased it by 19 percent for those with ischemic heart disease.

Oxford Street walkers who were healthy only had a 4.6 percent drop, coronary heart disease subjects saw 16 percent dip and those with ischemic heart disease only experienced a 8.6 percent reduction.

“Combined with evidence from other recent studies, our findings underscore that we can’t really tolerate the levels of air pollution that we currently find on our busy streets,” coauthor Fan Chung said in a statement.

They also suggest older adults walk in green spaces that are away from polluted or high-traffic areas.

“For many people, such as the elderly or those with chronic disease, the only exercise they very often can do is to walk,” Chung said. “We need to reduce pollution so that everyone can enjoy the benefits of physical activity in any urban environment.”